Numeric literals with underscores in JavaScript [duplicate]

Question

I recently ran into this code and I was wondering if there are any differences in writing those numeric literals in JavaScript with or without underscores:

let number = 1234567890;
console.log(number);

let number2 = 123_4567_890;
console.log(number2);

Semantics

Does this answer your question? Is there a Javascript equivalent to the Ruby syntax using underscores (e.g. 10_000 = 10000) to make larger integers human readable? – Marybelle

Answer 1

The point of the Numeric Seperators is to visually aid developers when dealing with big numbers. They don't change the actual code or its meaning.

Jeromejeromy

Answer 2

So after further reading, I see that ECMAScript 2021 has a new feature called Numeric separators which is used for larger numbers that are hard to read without separating them..

To improve readability, this feature enables underscores as separators in numeric literals as you can see in the following example for all kinds of numeric literals:

const readableMiliion = 1_000_000;
const regularMiliion = 1000000;

console.log(readableMiliion);
console.log(regularMiliion);     

const decimal = 1_000_000.220_720;
const binary = 0b01010110_00111000;
const hexa = 0x40_76_38_6A_73;

console.log(decimal);  
console.log(binary);  
console.log(hexa);  

More about Numeric Separators can be found on the following pages:

• https://v8.dev/features/numeric-separators
• https://writingjavascript.com/what-are-numeric-separators

Semantics